Graphite Component Testing on the Load Capacity of the Dowel-Brick Structure in HTR-PM

Graphite core components which form the moderator and reflector structures in High Temperature Reactor Pebble bed Module (HTR-PM) are subjected to various kinds of loads. Graphite keys and dowels are designed to maintain the structure integration and dimension stability of the graphite assembly during the operation of the plant. The dowel-brick structures bear the shear loads between different layers of the graphite bricks. Experiments have been carried out to study the shear load capacity of the graphite dowel and dowel-brick structure. The load-displacement curves and the failure modes were obtained for different dowels used in HTR-PM. The results show that for a dowel-brick structure subjected to lateral load, graphite brick failed first with cracks initiated around the dowel socket. The load capacity of the dowel-brick structure is lower than that of the dowel itself. The shear stiffness of the dowel-brick structure was obtained to calculate the relative displacement of adjacent graphite bricks connected by dowels.